Some communication devices well known in the art have is a function for printing image data received from an external device, and a function for displaying the received image data on a display unit prior to printing. For example, a communication device disclosed in Japanese unexamined patent application publication No. 2000-062288 allows the user to preview received image data on a display unit and to select only image data that must be printed, thereby preventing unnecessary consumption of paper and ink caused by printing unneeded image data.
Further, some copy machines well known in the art scan a plurality of sheets of an original and display the acquired image data on a display unit prior to printing. For example, the copy machine disclosed in US 2004/0165207 A1 sequentially scans 20 sheets of an original, accumulating the scanned image data, and generates confirmation image data from the accumulated image data to be displayed on the display unit. This image confirmation process (preview process) is performed when the user gives a command to the copy machine to execute the process. When the user gives a command to the copy machine to rescan the original after previewing the confirmation image data displayed on the display unit, the copy machine discards image data for the pages specified by the user and inserts rescanned image data for the same pages at the discarded page positions in the accumulated data. Once the user has previewed the scanned image data for the original and indicated to the copy machine that the scanning is complete, the copy machine prints the accumulated image data on recording paper. Hence, this type of copy machine allows the user to confirm scanned data for an original, even when the entire series of pages in the original have not yet been scanned.
However, these conventional copy machines wait for the user to issue an instruction or command to execute the image confirmation process prior to executing the preview process. Therefore, if the user wishes to view the image data for each sheet of the original, the user must input a command to execute the image confirmation process into the copy machine each time one of the sheets of original is scanned. Since the user must perform so many operations, the conventional copy machines have not been user-friendly.